Correct Answer: B. loving

Correct Answer: B. cheque stub

Correct Answer: B) Photon

Explanation

(a)(i) Characteristics of homologous series: –All members can be represented by a general molecular formular. –Each member of the series differs from the next by a constant/Fixed number of atom-CH\(_2\)/Successive member differs by CH–All members of the group have similar chemical proterties. –All members have same functional group. –All members of the; roup are prepared using similar/same general methods. All members of the series show a gradual change in physical properties (e.g. density, solubility, etc).

(ii) Groups of compounds which form such a series: –Alkanes –Alkenes –Alkynes –Alkanols –Alkanoic acid –Alkanoates.

(b) A saturated organic compound A containing two carbon atoms reacted with ethanoic acid in the presence of a mineral acid to form a compound B with a sweet smell: The functional group present in A. Hydroxy/Hydroxyl.

(ii) Structure of A.

(iii) Chemical equation to show the formation of B:

CH\(_3\)COOH + CH\(_3\)CH\(_2\)OH \(\rightleftharpoons\) CH\(_3\)COOH\(_2\)CH\(_3\) + H\(_2\)O.

(iv) Name of compound B: Ethyl ethanoate

(c)(i) Balance equation for reaction between Ethyne and Excess bromine:

C\(_2\)H\(_2\) + 2Br\(_2\) --> C\(_2\)H\(_2\) Br\(_4\)

OR

H— C \(\equiv\) C— H H 2Br\(_2\) —> H-CBr\(_2\)-CBr\(_2\)-H

(ii) IUPAC name of the product of the reaction in (c)(i) 1,1, 2, 2–tetrabromoethane.

(iii) Conditions under which cracking takes place: –High pressure –High temperature –Presence of a suitable catalyst.

(d)(i) Preparation of ethanol from starch: Treat starch with malt, diatase, convet starch to maltose.

2(C\(_6\) H\(_{(10)}\)O\(_5\) )n + nH\(_2\) O --> nC\(_{(12)}\) H\(_{(22)}\)O\(_{(11)}\). Add yeast. Ezyme maltase convert maltose to glucose.

C\(_{(12)}\)H\(_{(22)}\) + H\(_2\)O —> 2C\(_6\)H\(_{(12)}\)O\(_6\). Ezyme zymase convert glucose to maltase to ethanol and CO\(_2\)

C\(_6\)H\(_{(12)}\)O\(_6\) —> 2C\(_2\)H\(_5\)OH + 2CO\(_2\).

(ii) Properties of starch: –Can be hydrolysed. –Has no taste. –When suspension of starch is warmed, it forms colliodal solution. –It is insoluble in water. –It has no smell.

(iii) Reason why starch does not reduce Fehlings solution: It does not contain any free carbonyl group/No alkanol group/No hydrogen attached to the carbonyl group.

(iv) Chemical test to confirm the presence of starch: Add a few drops of iodine to a boiled starch. A dark-blue colouration appears.

Correct Answer: D. Promotion of a common lingua franca

Correct Answer: A. aerenchyma tissues

Correct Answer: D. Offset measurement

Correct Answer: B. clotting of blood

Correct Answer: D. be irrevocably committed

Explanation

The idiom to cross the Rubicon originates from Julius Caesar's decision to cross the Rubicon River with his army in 49 BC. This act was a declaration of war against the Roman Senate and was an irreversible step, signifying a point of no return. He famously said, alea iacta est (the die is cast).

Therefore, in modern usage, to cross the Rubicon means to pass a point of no return, to make an irreversible decision, or to commit oneself irrevocably to a course of action.

Let's look at the options:

• A. pass through a place called rubicon: This describes a literal action, not the idiomatic meaning.

• B. cross a river called rubicon: This describes the literal historical event, but not the figurative meaning of the idiom.

• C. cross a bridge called rubicon: This is incorrect; it was a river, not a bridge. Even if it were correct, it would still only describe a literal act.

• D. be irrevocably committed: Irrevocably means in a way that cannot be changed, reversed, or recovered; final. This perfectly captures the essence of the idiom – making a decision that cannot be undone, committing to a path with no turning back.

The sentence It is usually hard to change the course of action when one crosses the rubicon directly supports this meaning, implying that once the rubicon is crossed, changing the course is extremely difficult because a final commitment has been made.

The correct answer is D.

Correct Answer: D. phosphorus sulphide